Electronic control unit, frame generating method, and non-transitory computer-readable recording medium storing a program

ABSTRACT

An electronic control unit (ECU) is provided. The ECU is connected to a first network in an onboard network system. The onboard network system includes the first network and a second network. In the first network, first-type frames are transmitted following a first communication protocol. In the second network, second-type frames are transmitted following a second communication protocol. The first-type frame includes first information serving as a base for the second-type frame to be transmitted to the second network, and second information indicating that the first-type frame includes information that is to be transmitted to the second network. The ECU includes a generator that generates the first-type frame following the first communication protocol, and a transmitter that transmits, to the first network, the first-type frame generated by the generator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation of U.S. patent application Ser. No. 16/785,040,filed Feb. 7, 2020, which is a Continuation of U.S. patent applicationSer. No. 16/166,361, filed Oct. 22, 2018 and now U.S. Pat. No.10,601,607 issued Mar. 24, 2020, which is a Continuation ofInternational Pat. Appl. No. PCT/JP2017/015816, filed Apr. 20, 2017,which claims the benefit of U.S. Provisional Pat. Appl. No. 62/342,544,filed May 27, 2016, and priority to Japanese Pat. Appl. No. 2017-046566,filed Mar. 10, 2017. The disclosure of each of these documents,including the specification, drawings, and claims, is incorporatedherein by reference in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to message processing technology ofelectronic control units that communicate over an onboard network.

2. Description of the Related Art

Japanese Unexamined Patent Application Publication No. 2016-111477describes a gateway that relays messages among device conforming to theCAN protocol and device conforming to the Ethernet (registeredtrademark) protocol and so forth.

SUMMARY

Further improvement has been needed with the above related art.

In one general aspect, the techniques disclosed here feature anelectronic control unit connected to a first network in an onboardnetwork system. The onboard network system includes the first networkfor transmission of a first-type frame following a first communicationprotocol, and includes a second network for transmission of asecond-type frame following a second communication protocol that isdifferent from the first communication protocol. The electronic controlunit includes: a generator that generates the first-type frame followingthe first communication protocol; and a transmitter that transmits, tothe first network, the first-type frame generated by the generator. Thefirst-type frame includes first information serving as a base for thesecond-type frame to be transmitted to the second network, and secondinformation indicating that the first-type frame includes informationthat is to be transmitted to the second network.

According to the present disclosure, further improvement can berealized.

It should be noted that general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an overall configuration of an onboardnetwork system according to a first embodiment;

FIG. 2 is a diagram illustrating a schematic configuration of theonboard network according to the first embodiment;

FIG. 3 is a diagram illustrating a format for an Ethernet (registeredtrademark) frame (also referred to as “E-message”) format exchanged atpart of the onboard network according to the first embodiment;

FIG. 4 is a diagram illustrating an example of the configuration of anE-message payload (a configuration including one CAN messageinformation);

FIG. 5 is a diagram illustrating an example of the configuration of anE-message payload (a configuration including multiple of CAN messageinformation);

FIG. 6 is a diagram illustrating the format of a data frame stipulatedby the CAN protocol;

FIG. 7 is a configuration diagram of an electronic control units (E-ECU)according to the first embodiment;

FIG. 8 is a diagram illustrating an example of an addressee table usedby the E ECU according to the first embodiment;

FIG. 9 is a configuration diagram of a network hub according to thefirst embodiment;

FIG. 10 is a diagram illustrating an example of a MAC (Media AccessControl) address table used at the hub according to the firstembodiment;

FIG. 11 is a flowchart illustrating an example of operations of theE-ECU according to the first embodiment;

FIG. 12 is a flowchart illustrating an example of operations of the hubaccording to the first embodiment;

FIG. 13 is a sequence diagram illustrating an example of messagetransmission in the onboard network system according to the firstembodiment;

FIG. 14 is a diagram illustrating a schematic configuration of anonboard network according to a second embodiment;

FIG. 15 is a configuration diagram of a hub according to the secondembodiment;

FIG. 16 is a configuration diagram of a conversion device according tothe second embodiment;

FIG. 17 is a diagram illustrating a schematic configuration of anonboard network according to a third embodiment;

FIG. 18 is a configuration diagram of a hub according to the thirdembodiment;

FIG. 19 is a diagram illustrating an example of an addressee table usedat the hub according to the third embodiment;

FIG. 20 is a configuration diagram of a hub according to a fourthembodiment;

FIG. 21 is a flowchart illustrating an example of operations of theE-ECU according to the fourth embodiment;

FIG. 22 is a flowchart illustrating an example of operations of the hubaccording to the fourth embodiment;

FIG. 23 is a diagram illustrating an example of an addressee table usedat an E ECU according to a fifth embodiment;

FIG. 24 is a diagram illustrating an example of a correlation tablewhere MAC addresses and CAN-IDs are correlated: used at a hub accordingto the fifth embodiment;

FIG. 25 is a flowchart illustrating an example of operations of the hubaccording to the fifth embodiment;

FIG. 26 is a diagram illustrating a modification of the configuration ofan E-message payload;

FIG. 27 is a diagram illustrating an example of a correlation tablewhere positions of each individual data within an E-message payload: andCAN-IDs have been correlated, in the modification; and

FIG. 28 is a diagram illustrating a schematic configuration of anonboard network according to the modification.

DETAILED DESCRIPTION Underlying Knowledge Forming Basis of the PresentDisclosure

In recent years, a great number of devices called electronic controlunits (ECU) have been placed in systems in automobiles. A networkconnecting these ECUs is referred to as an onboard network. Manystandards exist for onboard networks. One of the most mainstream ofthese onboard networks is a standard called Controller Area Network(CAN), that is stipulated in ISO11898-1. In CAN, ECUs (nodes) connectedto a bus that is a wired transmission path (communication path) exchangeframes (messages). There are no identifiers indicating transmissiondestinations or transmission sources in CAN. A transmitting node appendsan ID (CAN-ID) to each frame and transmits (i.e., sends signals out ontothe bus), and the receiving nodes receive (i.e., read signals from thebus) only of messages of CAN-IDs set beforehand. There is a standardcalled Ethernet (registered trademark) stipulated by IEEE 802.3, as astandard to transmit a greater amount of information. A frame (message)in Ethernet (registered trademark) includes information indicating atransmission destination and a transmission source, in the header. Themaximum amount of data that can be transmitted by one frame is greaterin Ethernet (registered trademark) as compared to CAN.

In an onboard network including an Ethernet (registered trademark)network and a CAN network, each of the ECUs that communicate with otherelectronic control units will have an interface for at least one ofEthernet (registered trademark) and CAN. In this case, an arrangementwhere each of the electronic control units that need to performcommunication with electronic control units having an Ethernet(registered trademark) interface and also perform communication withelectronic control units connected to the CAN bus (i.e., electroniccontrol units having a CAN interface) have both interfaces has problemssuch as increased costs and so forth. Accordingly, an arrangement isdesirable where electronic control units having only an Ethernet(registered trademark) interface can transmit information to electroniccontrol units connected to the CAN bus via a gateway or the like. Notethat Japanese Unexamined Patent Application Publication No. 2016-111477makes no mention of how an electronic control unit having an Ethernet(registered trademark) interface (hereinafter, also referred to as“E-ECU”) should construct and transmit messages to an electronic controlunit connected to the CAN bus (hereinafter also referred to as “C-ECU”),and so forth.

The present Inventors have conceived the embodiments of the presentdisclosure based on the above-described consideration.

An electronic control unit (ECU) according to an aspect of the presentdisclosure is an electronic control unit connected to a first network inan onboard network system. The onboard network system includes the firstnetwork for transmission of a first-type frame following a firstcommunication protocol, and includes a second network for transmissionof a second-type frame following a second communication protocol that isdifferent from the first communication protocol. The electronic controlunit includes: a generator that generates the first-type frame followingthe first communication protocol; and a transmitter that transmits, tothe first network, the first-type frame generated by the generator. Thefirst-type frame includes first information serving as a base for thesecond-type frame to be transmitted to the second network, and secondinformation indicating that the first-type frame includes informationthat is to be transmitted to the second network. Accordingly, an ECUconnected to the first network such as Ethernet (registered trademark)or the like (e.g., an E-ECU) can appropriately transmit information toan ECU connected to the second network such as a CAN or the like (e.g.,a C-ECU) via the first network. Note that the first-type frametransmitted to this ECU (e.g., E-ECU) can be transmitted to an ECUconnected to the second network (e.g., C-ECU) with an appropriate pathhaving been selected by a network hub described next, for example. Thishub is a hub used in a network system including a first network and asecond network for example, and includes a reception circuit thatreceives the first-type frame, a transfer destination selecting circuitthat distinguishes whether or not the first type frame received by thereception circuit includes first information that serves as a base for asecond-type frame to be transmitted to the second network, and selects aport to send out a frame based on the first-type frame, based on theresults of this distinguishing, and a transmission circuit that sendsout a frame based on the first-type frame to a wired transmission pathconnected to a port selected by the transfer destination selectingcircuit with regard to the first-type frame received by the receptioncircuit.

The electronic control unit may further include a receiver that receivesexternal information from outside of the electronic control unit. Thegenerator may generate, in a first case, the first-type frame includingthe first information generated based on the external information andincluding the second information, and generate, in a second case, thefirst-type frame including information generated based on the externalinformation and including information that is contrary to the secondinformation. Accordingly, the hub or the like can appropriatelydistinguish transmission by the ECU of either the first-type frame to betransmitted to an ECU connected to the first network and the first-typeframe to be transmitted to an ECU connected to the second network. Thus,in either case, the first-type frame can be appropriately transmitted tothe intended ECU.

An arrangement may be made where the first communication protocol is anEthernet (registered trademark) protocol, the second communicationprotocol is a CAN protocol, the first-type frame is an Ethernet(registered trademark) frame including an Ethernet (registeredtrademark) header and data that is a payload, the second-type frame is adata frame including a data field, the first information indicatescontent of the data field, and the generator includes the firstinformation in the payload of the first-type frame. Accordingly, anE-ECU that only has an Ethernet (registered trademark) interface, forexample, can appropriately transmit information to a C-ECU connected tothe CAN bus.

The generator, in the generating of the first-type frame, may place anidentification flag in the first-type frame for identifying whether ornot the first-type frame includes information that is to be transmittedto the second network, and when generating the first-type frameincluding the first information, may set the identification flag in thefirst-type frame to a value indicating the second information.Accordingly, an appropriate transfer destination (i.e., the transferdestination of a frame based on the first-type frame) can be selected ata relay device such as a hub or the like connecting the first networkand the second network, based on the identification flag.

The generator may place the identification flag in the payload in thegenerating of the first-type frame. Accordingly, an identification flagcan be placed in the first-type frame without affecting the header ofthe first-type frame.

When generating the first-type frame including the first information,the generator may include a particular value set to indicate the secondinformation as a destination MAC address in the Ethernet (registeredtrademark) header in the first-type frame. Accordingly, the Ethernet(registered trademark) can be effectively used, and the data amount ofpayload can be reduced, for example.

The second-type frame may include an ID field, a data length code (DLC),and the data field, and the first information may indicate the ID field,the DLC, and a value of the data field. Accordingly, the ECU cantransmit primary information of the CAN message (e.g., a data framerelating to CAN) by the first-type frame. Thus, assuming a relay devicesuch as a hub or the like transmitting a CAN message based on thefirst-type frame, transmission of any CAN message to a C-ECU that is thetransmission destination of information can be realized.

The first information may indicate, for each of a plurality ofsecond-type frames to be transmitted to the second network, the IDfield, the DLC, and the value of the data field, and a quantity of theplurality of second-type frames. Accordingly, the transmissionefficiency in a case of transmitting information from an E-ECU to aC-ECU can be improved.

When generating the first-type frame including the first information,the generator may indicate the second information by setting a value ofa bit in a destination MAC address in the Ethernet (registeredtrademark) header in the first-type frame, the bit indicating whether ornot a global MAC address, to a value indicating not the global MACaddress, and the first-type frame include third information indicatingpart of the content of the second-type frame in the destination MACaddress. Accordingly, a CAN-ID or the like can be included as thedestination MAC address in the header of the first-type frame, and thedata amount of the payload can be reduced.

A frame generating method according to an aspect of the presentdisclosure is provided. The frame generating method generates a frame tobe transmitted, by an electronic control unit connected to a firstnetwork in an onboard network system. The onboard network systemincludes the first network for transmission of a first-type framefollowing a first communication protocol, and includes a second networkfor transmission of a second-type frame following a second communicationprotocol that is different from the communication protocol. Thefirst-type frame includes first information serving as a base for thesecond-type frame to be transmitted to the second network, and secondinformation indicating that the first-type frame includes informationthat is to be transmitted to the second network. Accordingly, an ECUconnected to the first network (e.g., an E-ECU) can appropriatelytransmit information to an ECU connected to the second network (e.g., aC-ECU) via the first network.

A program according to an aspect of the present disclosure is a programfor causing an electronic control unit that includes a microprocessorand that is connected to a first network in an onboard network system.The onboard network system includes the first network for transmissionof a first-type frame following a first communication protocol, andincludes a second network for transmission of a second-type framefollowing a second communication protocol that is different from thefirst communication protocol. The program causes the microprocessor toperform predetermined processing including generating the first-typeframe following the first communication protocol, and transmitting, tothe first network, the first-type frame generated in the generating. Thefirst-type frame includes first information serving as a base for thesecond-type frame to be transmitted to the second network, and secondinformation indicating that the first-type frame includes informationthat is to be transmitted to the second network. By installing andexecuting this program in an ECU that has a processor and that isconnected to the first network, that ECU can appropriately transmitinformation to an ECU connected to the second network (e.g., a C-ECU).

It should be noted that these general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, or a computer-readable recording medium such as a CD-ROM, andmay be realized by any combination of a system, method, integratedcircuit, computer program, and recording medium.

The following is a description of an onboard network system including anetwork hub and electronic control units (ECU) according to embodimentswith reference to the drawings. Note that the embodiments describedbelow are all specific examples of the present disclosure. Accordingly,values, components, placements and connected states of components, steps(processes) and the order of steps, and so forth illustrated in thefollowing embodiments, are only exemplary, and do not restrict thepresent disclosure. Components in the following embodiments which arenot included in an independent Claim are optionally addable components.The drawings are schematic diagrams, and are not necessarily created inan exact manner.

First Embodiment

An onboard network system 10 that includes multiple electronic controlunits (E-ECUs) that exchange Ethernet (registered trademark) frames(E-messages) following the Ethernet (registered trademark) protocol willbe described below with reference to the drawings, as an embodiment ofthe present disclosure. The onboard network system 10 also includesmultiple electronic control units (C-ECUs) that exchange data frames(CAN messages) and so forth following the CAN protocol.

1.1 Overall Configuration of Onboard Network System 10

FIG. 1 illustrates the overall configuration of the onboard networksystem 10 according to a first embodiment. The onboard network system 10is a network communication system in a vehicle where various types ofdevices have been installed, such as control devices, sensors,actuators, user interface devices, and so forth. The onboard networksystem 10 includes a first network where transmission of Ethernet(registered trademark) frames (E-messages) is performed following theEthernet (registered trademark) protocol (an Ethernet (registeredtrademark) network), and a second network where transmission of dataframes (CAN messages) is performed over a bus following the CAN protocol(a CAN network).

The onboard network system 10 includes a network hub 100, electroniccontrol units (E-ECUs) 200 a through 200 c, a CAN gateway 400,electronic control units (C-ECUs) 500 a through 500 d, various types ofdevices (communication module 300 a, rear camera 300 b, radar 300 c,engine 600 a, brakes 600 b, door open/close sensor 600 c, and windowopen/close sensor 600 d) connected to the electronic control units(E-ECUs and C-ECUs), cables (Ethernet (registered trademark) cables) 20a through 20 c, and busses (CAN busses) 30 a through 30 c, asillustrated in FIG. 1. The Ethernet (registered trademark) cables 20 athrough 20 c are first network transmission paths, and the busses 30 athrough 30 c are second network transmission paths.

Note that the onboard network system 10 may include many more ECUsbesides the E-ECUs 200 a through 200 c and C-ECUs 500 a through 500 d.For example, the C-ECUs that are omitted from illustration can beconnected to the busses 30 a through 30 c, besides the C-ECUs 500 athrough 500 d.

The ECUs (E-ECUs and C-ECUs) are devices that include, for example,processors (microprocessors), digital circuits such as memory and soforth, analog circuits, communication circuits, and so forth. The memoryis read-only memory (ROM), random access memory (RAM), and so forth, andcan store programs (computer programs serving as software) that areexecuted by processors. The memory may include non-volatile memory. AnECU realized various types of functions by a processor operating inaccordance with programs (computer programs), for example. Note that acomputer program is configured by combining multiple sets of commandcodes instructing commands with respect to the processor, to achievepredetermined functions.

The C-ECUs 500 a through 500 d exchange frames following the CANprotocol. The C-ECUs 500 a through 500 d are each connected to devicessuch as the engine 600 a, brakes 600 b, door open/close sensor 600 c,and window open/close sensor 600 d, obtain the states of the devices,and transmit data frames representing the states to the second networkmade up of the bus 30 a, bus 30 b, and so forth, periodically forexample. the C-ECUs 500 a through 500 d also receive data frames fromthe busses making up the second network, interpret the data frames,distinguish whether or not a data frame having a CAN-ID which it shouldreceive, and can control the device connected to the C-ECU in accordancewith the data in the data frame (the contents of the data field) asnecessary and can generate and transmit data frames as necessary.

The CAN gateway 400 is a type of ECU serving as a gateway (relay device,etc.) connected to the busses 30 a through 30 c. The CAN gateway 400 hasa function of transferring a data frame received from one bus to anotherbus.

The E-ECUs 200 a through 200 c have an Ethernet (registered trademark)interface, and connect to an Ethernet (registered trademark) cable. TheE-ECUs 200 a through 200 c transmit or receive Ethernet (registeredtrademark) frames (E-messages) following the Ethernet (registeredtrademark) protocol. The E-ECUs 200 a through 200 c are each connectedto a device such as the communication module 300 a, rear camera 300 b,and radar 300 c, perform processing based on information obtained fromthe devices, and can control devices as necessary, or transmitinformation to other ECUs as necessary. The communication module 300 ais a device that has a function of communicating with a server 90outside of the vehicle, via an external network 91 such as the Internetor the like. The server 90 is, for example, a computer having functionof providing information to the ECUs of the vehicle and so forth.

The hub 100 is an Ethernet (registered trademark) switch (switching hub)connected to the E-ECUs 200 a through 200 c. The hub 100 is alsoconnected to the bus 30 c, and has a function of transferring frames(messages) between the first network and second network. The hub 100includes digital circuits such as memory, analog circuits, communicationcircuits, and so forth, for example, and may include a processor.

1.2 Configuration of Onboard Network

FIG. 2 is a schematic configuration of the onboard network according tothe present embodiment. The E-ECUs 200 a through 200 c can communicatewith each other via the first network configured by connecting thecables at the hub 100, in the onboard network system 10. The C-ECUs 500a through 500 d also can communicate with each other via the secondnetwork configured from the busses 30 a and 30 b, the CAN gateway 400,and so forth. The E-ECU 200 a can communicate with the C-ECU 500 a viathe cable 20 a, hub 100, bus 30 c, CAN gateway 400, and bus 30 a.

The hub 100 has multiple ports for connecting to E-ECUs (e.g., terminalsfor connecting Ethernet (registered trademark) cables). The hub 100 alsohas one port (CAN port) for connecting to the bus 30 c connected to theCAN gateway 400.

1.3 Configuration of Frames Exchanged Over Onboard Network

FIG. 3 illustrates the format of a frame (E-message) exchanged over thefirst network. As illustrated in FIG. 3, The E-message is configured byadding a header (Ethernet (registered trademark) header) before apayload that stores data, which is the principal content oftransmission. The header includes a destination MAC address, source MACaddress, and type.

The E-ECUs in the onboard network system 10 transmit E-messagesincluding CAN message information when transmitting information to betransmitted to a C-ECU. CAN message information is information servingas a base for data frames (CAN message) transmitted over the CAN bus.

A data configuration example within the payload of the E-messageillustrated in FIG. 3 is illustrated in FIGS. 4 and 5. FIG. 4illustrates an example where just one CAN message information isincluded in the payload of an E-message, FIG. 5 illustrates an exampleof a case where including multiple CAN message information in thepayload of an E-message is enabled.

The CAN message information is made up of a CAN-ID, size, and data, inthe example in FIGS. 4 and 5. The number of messages in FIG. 5 indicatesthe number of CAN message information. Note that information indicatingthe data amount of the entire CAN message information or the like may beused instead of the number of messages. A CAN flag is an identificationflag for identifying whether or not an E-message includes information tobe transmitted to the second network, and is a flag that is set to ON ina case where CAN message information is included in the payload of anE-message (i.e., in a case where the ECU that is the destination of theE-message is a C-ECU), and other wise is set to OFF (i.e., a valueindicating information opposite to ON). Although the examples in FIGS. 4and 5 illustrate an example where a CAN flag is situated at the head ofthe payload of the E-message, this is only an example. An arrangementwhere multiple CAN message information can be included in an E-message,as in FIG. 5, will be primarily described in the present embodiment.This enables transmission efficiency to be improved, for example.

Note that in a case of an E-ECU transmitting information to betransmitted to an E-ECU but there is no need to transmit to a C-ECU, CANmessage information does not have to be included in the contents of thepayload of the E-message. In this case, if whether the destination ofthe E-message is a C-ECU or not can only be distinguished by the CANflag or the like, the E-ECU sets the CAN flag (see FIGS. 4 and 5) in thepayload of the E-message that does not need to be transmitted to a C-ECUto OFF, for example.

The C-ECUs 500 a through 500 d and so forth exchange frames followingthe CAN protocol in the second network. Frames in the CAN protocolinclude data frames, remote frames, overload frames, and error frames.Data frames will be described with primary focus here.

FIG. 6 illustrates the format of a data frame (CAN message) exchangedover the second network. A data frame includes a start of frame (SOF),ID (CAN-ID), remote transmission request (RTR), identifier extension(IDE), reserved bit “r”, size data, cyclic redundancy check (CRC)sequence, CRC delimiter “DEL”, acknowledgement (ACK) slot, ACK delimiter“DEL”, and end of frame (EOF), as illustrated in FIG. 6. The ID (CAN-ID)serving as the content of the ID field is an identifier indicating thetype of data, and also is referred to as a message ID. Note that in CAN,in a case where multiple nodes start transmission at the same time,communication arbitration is performed, where a frame having thesmallest CAN-ID value is given priority. Size is a data length code(DLC) indicating the length of the following data field (data). The dataspecification is not stipulated in the CAN protocol, and is set in theonboard network system 10. Accordingly, the specification can bedependent on the model of the vehicle, the manufacturer (automaker), orthe like.

1.4 Configuration of E-ECU

FIG. 7 is a configuration diagram of the E-ECU 200 a. The E-ECU 200 a isconfigured including a reception unit 210, a generating unit 220, and atransmission unit 230. These components are realized by communicationcircuits in the E-ECU 200 a, a processor or digital circuits executingprograms stored in the memory, and so forth.

The reception unit 210 receives external information, i.e., informationfrom outside of the E-ECU 200 a. The reception unit 210 includes anE-reception unit 211 and a data reception unit 212. The E-reception unit211 receives frames (E-messages) via the cable 20 a. The data receptionunit 212 receives data from a device to which it is connected(communication module 300 a).

The generating unit 220 generates E-messages following the Ethernet(registered trademark) protocol. The generating unit 220 includes a dataprocessing unit 221, a transmission destination determining unit 222, amessage constructing unit 223, and a CAN message constructing unit 224.

The data processing unit 221 performs information processing(computation, etc.) based on external information (data or E-message)received by one or both of the E-reception unit 211 and data receptionunit 212, and generates various types of information to be transmittedto other ECUs. The data processing unit 221 may use external informationitself as the generated various types of information. The informationprocessing by the data processing unit 221 may be any informationprocessing, and the information generated by the data processing unit221 may be any information. The various types of information that thedata processing unit 221 generates is information for traveling controlof the vehicle, information to be presented to the user of the vehicle,or the like, for example, and is classified into multiple types (datatypes) such as steering instruction angles, speed instruction values,current speed value, communication information, and so forth, forexample.

The transmission destination determining unit 222 determines atransmission destination using an addressee table for example, inaccordance with the data type of the information that the dataprocessing unit 221 has generated. FIG. 8 illustrates an example of theaddressee table that the transmission destination determining unit 222uses. The addressee table exemplarily illustrated in FIG. 7 is a tablecorrelating the transmission destination type, which indicates whetherthe ECU that is the destination of the information is an E-ECU or aC-ECU, and a destination MAC address (or CAN-ID), for each data type ofinformation. The in a case of having determined that the transmissiondestination of the information that the data processing unit 221 hasgenerated is a C-ECU, the transmission destination determining unit 222sets a CAN-ID based on the addressee table and notifies the CAN messageconstructing unit 224. The transmission destination determining unit 222also sets a destination MAC address that is to be the transmissiondestination of the information generated by the data processing unit221, using the addressee table, and notifies the E-message constructingunit 223. Note that in a case where the transmission destination ismultiple E-ECUs, the transmission destination determining unit 222notifies the E-message constructing unit 223 of the destination MACaddresses of each transmission destination. In a case of havingdetermined that the transmission destination is a C-ECU, thetransmission destination determining unit 222 sets a particular addressdecided beforehand as the destination MAC address, and notifies themessage constructing unit 223. Examples of a particular address includea broadcast address, multicast address, MAC address of a device(converter) having protocol conversion functions, and so forth. Notethat the hub 100 may have a MAC address although the hub 100 does notneed to have a MAC address, and in a case where the hub 100 has a MACaddress, that MAC address may be the above-described particular address.

The CAN message constructing unit 224 generates CAN message informationbased on the notified CAN-ID, the data indicating the information thatthe data processing unit 221 has generated, and the size of that data.For example, in a case where the data indicating the information thatthe data processing unit 221 has generated exceeds the maximum datalength of a CAN message, the CAN message constructing unit 224 generatesmultiple CAN message information by splitting the data indicating thatinformation. The CAN message information generated by the CAN messageconstructing unit 224 is placed in an E-message by the E-messageconstructing unit 223, and the E-message is transmitted by thetransmission unit 230. As long as the CAN message information generatedby the CAN message constructing unit 224 includes information indicatingat least the data of the CAN message (the content of the data field ofthe data frame), other contents and formats are optional. However,configuring the CAN message information so that the bit length of theCAN-ID, size, and data, follow the CAN protocol as illustrated in FIG.6, is useful. Also useful is the CAN message constructing unit 224constructing the CAN message information to match the CAN message formatin accordance with the CAN protocol, for example, so that a device suchas the hub 100 or the like can efficiently convert into CAN messagesduring the process of transmission of an E-message including CAN messageinformation to be transmitted to a C-ECU.

For every destination MAC address notified to the transmissiondestination determining unit 222, the E-message constructing unit 223constructs an E-message including that destination MAC address and theMAC address of the E-ECU 200 a serving as a source MAC address (see FIG.3). If the transmission destination is a C-ECU for example, theE-message constructing unit 223 includes the CAN flag set to ON, thenumber of CAN message information constructed by the CAN messageconstructing unit 224, and each CAN message information in the payloadof the E-message (see FIG. 5). If the transmission destination is anE-ECU for example, the E-message constructing unit 223 includes the CANflag set to OFF, and data indicating the information that the dataprocessing unit 221 has generated, in the payload of the E-message. Notethat in a case where the information generated by the data processingunit 221 is a plurality, the E-message constructing unit 223 may linkthe multiple CAN message information that can have different CAN-IDsfrom each other, that have been generated by the CAN messageconstructing unit 224, and place in the payload of the E-message.

In a case where a need has arisen to transmit CAN message information toa C-ECU based on external information (data or E-message) received fromone or both of the E-reception unit 211 and data reception unit 212 asdescribed above, the generating unit 220 generates an E-message storingthe CAN message information and a CAN flag set to ON. The CAN flag setto ON is used as second information indicating that the E-messageindicates first information (CAN message information that is the basefor a CAN message) that is to be transmitted to the second network.Also, in a case where a need has arisen to transmit information to anE-ECU based on the external information, the generating unit 220generates an E-message including the information to be transmitted, butnot including the second information (e.g., the CAN flag is set to OFF),for example. The transmission unit 230 sends the E-message generated bythe generating unit 220 out onto the cable 20 a, thereby transmitting tothe first network. Also note that the E-ECUs 200 b and 200 c also havethe same configuration as the above-described E-ECU 200 a.

1.5 Configuration of Hub 100

FIG. 9 is a configuration diagram of the hub 100. The hub 100 has ports1 through 4. The ports 1 through 3 are respectively connected to thecables 20 a through 20 c making up the first network. The port 4 is aCAN port where the bus 30 c making up the second network (i.e., thewired transmission path connected to the CAN gateway 400) is connected.The hub 100 is configured including a reception unit 110, a transferdestination selecting unit 120, and a transmission unit 130. Thesecomponents are realized by communication circuits in the hub 100,digital circuits (or a processor executing programs stored in thememory), and so forth.

The reception unit 110 includes an E-reception unit 111 that receivesE-messages from the ports 1 through 3, and a C-reception unit 112 thatreceives CAN messages from the port 4.

The transfer destination selecting unit 120 distinguishes whether or notan E-message received by the reception unit 110 includes firstinformation (CAN message information) that is the base of a CAN message(data frame) to be transmitted to the second network, and selects theport for sending out the frame based on the E-message, in accordancewith the results of the distinguishing. That is to say, in a case wherethe E-message received at the reception unit 110 does not include CANmessage information, the transfer destination selecting unit 120selects, based on the destination MAC address in the header of thatE-message, one of ports 1 through 3 as the destination for sending outan E message having the same contents as that E-message. The transferdestination selecting unit 120 selects a port by referencing a MACaddress table. FIG. 10 illustrates an example of a MAC address tableused by the transfer destination selecting unit 120. The MAC addresstable is generated and updated by the hub 100 serving as a switch(switching hub) learning MAC addresses by reception of E-messages fromeach of the ports 1 through 3. The above-described particular address,for example, may be set as the destination MAC address relating to theport 4 (CAN port) in the MAC address table. Note that an arrangement maybe made where, in a case where whether or not an E-message contains CANmessage information can be distinguished by the CAN flag placed in thepayload, information of the port 4 (CAN port) is not included in the MACaddress table. In a case where the E-message received by the receptionunit 110 includes CAN message information, the transfer destinationselecting unit 120 selects the port 4 (CAN port) as the sendingdestination of the CAN message (data frame) configured to indicate thatCAN message information, regardless of whether the distinguishing ismade based on the destination MAC address of the E-message or based onthe CAN flag in the E-message.

The transmission unit 130 includes an E-transmission unit 131, aC-transmission unit 132, a linking unit 133, and a splitting unit 134.The E transmission unit 131 has a function of transmitting E-messagesfrom the ports 1 through 3, and the C-transmission unit 132 has afunction of transmitting a CAN message in accordance from the CANprotocol from the port 4. The linking unit 133 has a function of linkinginformation regarding multiple CAN message received at the C-receptionunit 112 to generate an E-message for transmission, and hand this to theE-transmission unit 131. The splitting unit 134 has a function of, in acase where the payload of an E-message received at the E-reception unit111 contains multiple CAN message information that have been linked (seeFIG. 5) or the like, spiting into each individual CAN messageinformation of the number indicated by the number of messages in FIG. 5for example, and generating and sequentially transmitting CAN messagesfollowing the CAN protocol in accordance with each CAN messageinformation to the C-transmission unit 132. The order of transmission inthis case, i.e., the transmission order of the CAN messages to betransmitted at the C-transmission unit 132, follows the order of arrayof the CAN message information in the payload of the E-message servingas the base thereof, for example. According to these configurations, thetransmission unit 130 sends out a frame (an E message in a case whereany one of ports 1 through 3 has been selected, and a CAN message in acase where port 4 has been selected) based on the received E-message, tothe wired transmission path (one of cables 20 a through 20 c and bus 30c) connected to the port selected at the transfer destination selectingunit 120 with respect to the E-message received at the reception unit110. That is to say, in a case where the port selected by the transferdestination selecting unit 120 with respect to the E-message received atthe reception unit 110 is any one of ports 1 through 3, the transmissionunit 130 sends out an E-message of which at least the contents of thepayload are the same as that E-message to the cable connected to theselected port. In a case where the port selected by the transferdestination selecting unit 120 with respect to the E-message received atthe reception unit 110 is port 4 (CAN port) connected to the bus 30 c,the transmission unit 130 sends out a CAN message including the firstinformation (CAN message information) in that E-message to the bus 30 c.In detail, the transmission unit 130 sends out a CAN message to the bus30 c by placing the ID (i.e., the value of the ID field) of the firstinformation (CAN message information) in the E-message that the hub 100has received into the ID field of the CAN message, placing the size thatthe first information indicates (i.e., value of DLC) into the DLC of theCAN message, places data that the first information indicates (i.e.,values in the data field) into the data field of the CAN message, andsending out the generated CAN message to the bus 30 c. Also, in a casewhere an E-message that the hub 100 has received has first informationincluding multiple CAN message information in the payload, thetransmission unit 130 performs sending out of CAN messages to the bus 30c by sequentially sending out each of the multiple CAN messagesincluding parts different from each other in the first information(individual CAN message information) in the E-message that the hub 100has received. Note that the hub 100 may have functions to generateE-messages based on CAN messages received at the C-reception unit 112,and transmit from one of the ports 1 through 3.

1.6 Operations of E-ECU

FIG. 11 is a flowchart illustrating E-ECU processing, as an example ofoperations of an E-ECU according to the present embodiment. E-ECUprocessing executed by the E-ECU 200 a will be described below by way ofFIG. 11.

The E-ECU 200 a receives external information (an E-message from anotherE-ECU, data from the communication module 300 a, etc.) from thereception unit 210 (step S1).

Next, based on the external information that has been received, theE-ECU 200 a performs data processing (generating various types ofinformation to be transmitted to another ECU, etc.) at the dataprocessing unit 221 (step S2).

The ECU 200 a then determines, regarding each information generated bythe data processing unit 221, whether the transmission destination ofthe information is a C-ECU or not in accordance with the data type ofthe information, using an addressee table (step S3), In a case of havingdetermined that the transmission destination of the information is aC-ECU, the E-ECU 200 a sets a CAN-ID in accordance with the data type ofthe information, and generates CAN message information indicating theCAN-ID, the data indicating the information generated by the dataprocessing unit 221, and the size of the data, using the CAN messageconstructing 224 (step S4). Note that in a case where the dataindicating the information generated by the data processing unit 221exceeds the maximum data length of a CAN message, the data is split, andmultiple CAN message information are generated, as described earlier.

The E-ECU 200 a also determines whether or not there is a need totransmit multiple CAN message information (step S5), and if there isthat need, joins (links) each of the CAN message information generatedin step S4 (step S6). In a case where multiple CAN message informationhave been generated by spotting data indicating the informationgenerated by the data processing unit 221, or in a case where the dataprocessing unit 221 has generated multiple information, determination ismade in step S5 that there is a need to transmit multiple CAN messages.The E-ECU 200 a skips step S6 in a case of having determined that thereis no need to transmit multiple CAN messages.

In a case of having determined in step S3 that the transmissiondestination is a C-ECU, the E-ECU 200 a constructs an E-messageincluding one CAN message information generated in step 34, or multipleCAN message information linked in step S6, in the payload, using themessage constructing unit 223 (step S7). In a case where the E-ECU 200 ahas determined in step S3 that the transmission destination is not aC-ECU, in step S7 an E-message including the data indicating theinformation generated by the data processing unit 221 in the payload isconstructed by the message constructing unit 223. As one example, instep S7 the E-ECU 200 a generates an E-message storing in the payloadthereof the CAN message information to be transmitted to a C-ECU and aCAN flag set to ON, or an E-message storing in the payload thereof theCAN message information to be transmitted to an E-ECU and a CAN flag setto OFF. Note that a destination MAC address set in accordance with thedata type of information to be transmitted using the addressee table isset in the header of an E-message of which the transmission destinationis not a C-ECU. Also, a destination MAC address indicating theabove-described particular address is set in the header of an E-messageof which the transmission destination is a C-ECU.

The E-ECU 200 a transmits the E-message generated in step S7 to thecable 20 a (step S8) by the transmission unit 230. The Emessagetransmitted by the E-ECU 200 a will be received by the hub 100.

Note that the E-ECU 200 b and E-ECU 200 c can also operate in the sameway as the E-ECU 200 a.

1.7 Operations of Hub 100

FIG. 12 is a flowchart illustrating hub processing, as an example ofoperations of the hub 100. hub processing is processing to transfer anB-message in a case of having received an Emessage. Transfer of anEmessage here is transmission of the same E-message as the E-messagereceived, or transmission of a CAN message based on the receivedE-message. hub processing executed by the hub 100 will be describedbelow by way of FIG. 12.

The hub 100 receives an E-message from one of ports 1 through 3 (StepS11).

The hub determines whether or not the CAN flag in the received E-messageis ON (step S12). If the CAN flag is ON, the received E-message willinclude first information (CAN message information) serving as the basefor a CAN message to be transmitted to the second network, and if OFF,the E-message does not include first information.

If the CAN flag is OFF, the hub 100 uses the MAC address table to selecta port corresponding to the destination E-ECU (destination MAC address)by the transfer destination selecting unit 120 (step S13). The hub 100then sends out the same E-message as the received E-message from theport selected in step S13 (step S14), and ends processing of handlingthe received E-message.

In a case of having determined in step S12 that the CAN flag is ON, thehub 100 distinguishes whether or not multiple CAN message informationare included in the received B-message based on the number of messageillustrated in FIG. 5 for example (step S15), and in a case wheremultiple CAN message information are included, splits into individualCAN message information (step S16).

The hub 100 generates a CAN message based on each CAN messageinformation split in step S16, or, in a case of having distinguished instep S15 that only one CAN message information is included, based onthat CAN message information (step S17). In a case where the CAN messageinformation is configured of CAN-ID, size, and data, for example (seeFIG. 5), the hub 100 generates a CAN message including the CAN-1D, size,and data (See FIG. 6). The hub 100 then sequentially sends out thegenerated CAN messages to the bus 30 c from the port 4 (CAN port) so asto be transmitted to the CAN gateway 400 (step S18), and ends processingof handling the received E-message.

Upon a CAN message having been sent out from the hub 100 to the bus 30c, the CAN gateway 400 transfers that CAN message to both or one of thebus 30 a and bus 30 b, for example, based on transfer rules decidedbeforehand. As an example of transfer rules for the CAN gateway 400,rules stipulating the bus to be transferred to according to the CAN-1D,or the like, are used.

1.8 Transmission Sequence of Message from E-ECU to C-ECU

FIG. 13 is a sequent diagram illustrating an example of messagetransmission in the onboard network system 10, Transfer of informationfrom an ECU connected to the first network (E-ECU) to an ECU connectedto the second network (C-ECU) will be described below by way of FIG. 13.

The E-ECU 200 a transmits an E-message including three CAN messageinformation including different CAN-IDs from each other, to the hub 100via the cable 20 a, as an E-message indicating a CAN message (stepS101).

The hub that has received the E-message judges whether or not theE-message indicates a CAN message, from the CAN flag and so forth (stepS102), and in a case of indicating a CAN message, splits the linked CANmessage information included in the E-message into three individual CANmessage information, as necessary (step S103).

The hub 100 then sequentially transmits the three CAN messages to thebus 30 c, based on each of the CAN-ID, size, and data, of the three CANmessage information (steps S104 through S106). Accordingly, the CANgateway 400 receives the three CAN messages, and transfers the CANmessages to the busses selected based on the transfer rules, inaccordance with the CAN-IDs of the received CAN messages (steps S107through S109).

1.9 Advantages of First Embodiment

In a case where the E-ECU 200 a is to transmit information to a C-ECU inthe onboard network system 10 according to the first embodiment, anE-message is transmitted that includes CAN message information, a CANflag, and so forth. Accordingly, the hub 100 will be able toappropriately select the destination of the CAN message indicated by theE-message. According to the method where a CAN flag is included in theE-message and the indicates whether or not the E-message includes CANmessage information, whether or not the CAN message should be sent tothe CAN bus can be identified based on the E-message, even in a casewhere the destination MAC address of the E-message is a broadcastaddress, for example. Also, the E-ECU 200 a can include multiple CANmessage information serving as bases for multiple CAN messages inE-messages. Accordingly, information transmission efficiency can beincreased.

Second Embodiment

An example where the configuration of the in the onboard network system10 illustrated in the first embodiment has been partially modified willbe described below. The onboard network system according to a secondembodiment is an arrangement where a conversion device is disposedbetween the hub 100 and bus 30 c in the onboard network system 10illustrated in the first embodiment (see FIG. 1), and the hub 100 ismodified. Note that components in the onboard network system accordingto the present embodiment that are the same as those in the firstembodiment are denoted by the same reference numerals as in the firstembodiment, and description will be omitted. Points regarding theonboard network system according to the present embodiment that are notdescribed in particular as the same as in the onboard network system 10illustrated in the first embodiment.

2.1 Configuration of Onboard Network

FIG. 14 illustrates a schematic configuration of an onboard networkaccording to the present embodiment. The onboard network according tothe present embodiment is an arrangement where the hub 100 in theonboard network illustrated in the first embodiment (see FIG. 2) hasbeen replaced by a hub 100 a and a conversion device 700 and a cable 20d have been added.

The hub 100 a does not have CAN ports but has multiple ports, to whichthe cables 20 a through 20 d that are Ethernet (registered trademark)cables are connected. The hub 100 a is connected to the conversiondevice 700 by the cable 20 d, and the conversion device 700 is connectedto the CAN gateway 400 by the bus 30 c.

The E-ECUs 200 a through 200 c in the onboard network system accordingto the present embodiment can communicate with each other via the firstnetwork configured by connecting the cables to the hub 100 a. The C-ECUs500 a through 500 d can communicate with each other via the secondnetwork configured of the busses 30 a and 30 b, the CAN gateway 400, andso forth. Also, for example, the E-ECU 200 a can communicate with theC-ECU 500 a via the cable 20 a, hub 100 a, cable 20 d, conversion device700, bus 30 c, CAN gateway 400, and bus 30 a.

2.2 Configuration of Hub 100 a

FIG. 15 is a configuration diagram of the hub 100 a. The hub 100 a is apartial modification of the hub 100 illustrated in the first embodiment,and points that are not illustrated here in particular are the same aswith the hub 100. The hub 100 a has ports 1 through 3 and a port A. Theports 1 through 3 and port A are respectively connected to the cables 20a through 20 d making up the first network. The port A is connected tothe cable 20 d connected to the conversion device 700. The hub 100 a isconfigured including a reception unit 110 a, a transfer destinationselecting unit 120 a, and a transmission unit 130 a, and transfers Emessages. These components are realized by communication circuits in thehub 100 a, memory, digital circuits (or a processor executing programsstored in the memory), and so forth.

The reception unit 110 a includes the E-reception unit 111 that receivesE messages from the ports 1 through 3 and port A.

The transfer destination selecting unit 120 a is a partial modificationof the transfer destination selecting unit 120 illustrated in the firstembodiment, and points that are not illustrated here in particular arethe same as the transfer destination selecting unit 120. The transferdestination selecting unit 120 a distinguishes whether or not anE-message received by the reception unit 110 a includes firstinformation (CAN message information) serving as the base for a CANmessage (data frame) to be transmitted to the second network, andselects the port for sending out the frame based on the E-message, basedon the distinguishing results. That is to say, in a case where theE-message received at the reception unit 110 a does not include CANmessage information, the transfer destination selecting unit 120 aselects one of ports 1 through 3 as the destination to send E-messagesof similar contents as that E-message, based on the destination MACaddress in the header of that E-message. The transfer destinationselecting unit 120 a selects the port by referencing a MAC addresstable. The destination MAC address regarding the port Ain the MACaddress table may be set to the particular address illustrated in thefirst embodiment, or the MAC address of the conversion device 700 may beset, for example. Also, the hub 100 a may learn the MAC address of theconversion device 700 and update the MAC address table. In a case wherethe MAC address of the conversion device 700 is set as the destinationMAC address regarding the port Ain the MAC address table, the E-ECU 200a or the like that is the transmission source of the E-message includingCAN message information may specify the MAC address of the conversiondevice 700 as the destination MAC address in the header of theE-message, for example. In this case, the transfer destination selectingunit 120 a may select the port in accordance with the MAC address table,without confirming whether or not the E-message contains CAN messageinformation. An arrangement may be made where, a case where whether ornot the E-message contains CAN message information can be distinguishedby the CAN flag set in the payload, information of the port A is notincluded in the MAC address table. In a case where the E-messagereceived at the reception unit 110 a includes CAN message information,the transfer destination selecting unit 120 a selects the port A (portconnected to a device connected to the bus 30 c, by the cable 20 d) asthe sending destination of E-messages that are the same as the receivedE-message, regardless of whether the distinguishing is made based on thedestination MAC address of the E-message or based on the CAN flag in theE-message.

The transmission unit 130 a includes the E-transmission unit 131 thattransmits E-messages that are the same as the E-message received at theE reception unit 111 (or E-messages of which at least the contents ofthe payload are the same) from the port (port 1 through 3 or port A)selected by the transfer destination selecting unit 120 a (i.e., sendsout onto the cable connected to that port).

2.3 Configuration of Conversion Device 700

FIG. 16 is a configuration diagram of the conversion device 700. Theconversion device 700 is configured of, for example, a processor,digital circuits such as memory and so forth, analog circuits,communication circuits, and so forth.

The conversion device 700 has a function of converting E-messages intoCAN messages, and includes a reception unit 710, a transfer destinationdetermining unit 720, a splitting unit 730, and a CAN transmission unit740, as functional components for realizing this function. Thesefunctional components are realized by a communication circuit in theconversion device 700, a processor executing programs stored in memory,and so forth. Note that the conversion device 700 may have a function ofconverting CAN messages into E-messages.

The reception unit 710 receives E-messages from the cable 20 d. Thetransfer destination determining unit 720 distinguishes whether or notan E message received by the reception unit 710 includes firstinformation (CAN message information) serving as a base for a CANmessage (data frame) to be transmitted to the second network, anddetermines whether or not a CAN message based on the E-message should besent out to the bus 30 c, based on the results of the distinguishing. Ina case where the E-message received by the reception unit 710 does notinclude CAN message information, for example, the transfer destinationdetermining unit 720 determines that a CAN message should not be sentout to the bus 30 c, and discards that E-message. In a case where theE-message received by the reception unit 710 includes CAN messageinformation, the transfer destination determining unit 720 notifies thesplitting unit 730 regarding the content of the payload of theE-message.

The splitting unit 730 has a function where, in a case where multiplelinked CAN message information are included as the content of thepayload of the E-message notified thereto (see FIG. 5), the splittingunit 730 splits this into individual CAN message information of thenumber indicated by the number of messages in FIG. 5 for example,generates the CAN messages following the CAN protocol in accordance withthe CAN message information, and sequentially transmits these to the CANtransmission unit 740. The order of transmission in this case followsthe order of array of the CAN message information in the payload of theE-message, for example. In a case where one CAN message information isincluded as the content of the payload of the E-message notifiedthereto, the splitting unit 730 generates a CAN message following theCAN protocol in accordance with the CAN message, and transmits this tothe CAN transmission unit 740.

The CAN transmission unit 740 sequentially transmits the CAN messages tothe bus 30 c making up the second network, in the order of transmissionfrom the splitting unit 730, following the CAN protocol. Accordingly,the CAN message is transferred to an appropriate bus by the CAN gateway400 connected to the bus 30 c, and received by a C-ECU.

2.4 Advantages of Second Embodiment

In the onboard network system according to the second embodiment, in acase of the E-ECU 200 a transmitting information to a C-ECU, anE-message containing CAN message information, a CAN flag, and so forth,is transmitted. This enables the hub 100 a to appropriately select thetransmission destination of the E-message containing the CAN messageinformation. According to the method where a CAN flag is included in theE-message and the E-message includes CAN message information, the hub100 a can transmit just E-messages containing CAN message information tothe conversion device 700 having a function to convert to CAN messages,even in a case where the destination MAC address of the E-message is abroadcast address, for example. Note that an arrangement may be madewhere the conversion device 700 is connected to both a first networkwhere transmission of first-type frames (e.g., Ethernet (registeredtrademark) frames) is performed following a first communication protocol(e.g., Ethernet (registered trademark) protocol), and a second networkwhere transmission of second-type frames (e.g., CAN messages that aredata frames) is performed following a second communication protocol(e.g., CAN protocol) that is different form the first communicationprotocol, and includes a reception unit that receives first-type framesfrom the first network, and a transmission unit that, in a case where afirst-type frame received by the reception unit includes firstinformation serving as a base for a second type frame to be transmittedto the second network, a frame (e.g., CAN message) based on thefirst-type frame is sent out to the second network.

Third Embodiment

Another example where the configuration of the onboard network in theonboard network system 10 illustrated in the first embodiment has beenpartially modified, will be described below. The onboard network systemaccording to a third embodiment is an arrangement where the hub 100 inthe onboard network system 10 illustrated in the first embodiment (seeFIG. 1) also includes the functions of the CAN gateway 400. Note thatcomponents in the onboard network system according to the presentembodiment that are the same as those in the first embodiment aredenoted by the same reference numerals as in the first embodiment, anddescription will be omitted. Points regarding the onboard network systemaccording to the present embodiment that are not described in particularas the same as in the onboard network system 10 illustrated in the firstembodiment.

3.1 Configuration of Onboard Network

FIG. 17 illustrates a schematic configuration of an onboard networkaccording to the present embodiment. The onboard network according tothe present embodiment is an arrangement where the CAN gateway 400 andbus 30 c in the onboard network illustrated in the first embodiment (seeFIG. 2) have been omitted, and the hub 100 has been replaced by a hub100 b including the same function as the CAN gateway 400.

The hub 100 b has multiple ports for connecting to E-ECUs (i.e.,terminals for connecting Ethernet (registered trademark) cables). Thehub 100 b also has multiple ports for connecting to busses to which oneor multiple C-ECUs are connected (i.e., terminals for connecting tobusses). That is to say, the hub 100 b has ports to connect to thecables 20 a through 20 c, and to the busses 30 a and 30 b.

The E-ECUs 200 a through 200 c in the onboard network system accordingto the present embodiment can communicate with each other via the firstnetwork configured by connecting the cables to the hub 100 b. The C-ECUs500 a through 500 d can communicate with each other via the secondnetwork configured of the busses 30 a and 30 b. Also, for example, theE-ECU 200 a can communicate with the C-ECU 500 a via the cable 20 a, hub100 b, and bus 30 a.

3.2 Configuration of Hub 100 b

FIG. 18 is a configuration diagram of the hub 100 b. The hub 100 b hasports 1 through 5. The ports 1 through 3 are respectively connected tothe cables 20 a through 20 c making up the first network. The port 4(CAN port 1) and port 5 (CAN port 2) are respectively connected to thebusses 30 a and 30 b making up the second network. Although the hub 100b may have three or more CAN ports, an example of having two isillustrated here, for the sake of convenience of description. The hub100 b includes the reception unit 110, a transfer destination selectingunit 120 b, and the transmission unit 130, as illustrated in FIG. 18.These components are realized by communication circuits in the hub 100b, memory, digital circuits (or a processor executing programs stored inthe memory), and so forth.

The reception unit 110 includes the E-reception unit 111 that receivesE-messages from the ports 1 through 3, and the C-reception unit 112 thatreceives CAN messages from the ports 4 and 5.

The transfer destination selecting unit 120 b distinguishes whether ornot an E-message received by the reception unit 110 includes firstinformation (CAN message information) serving as the base of a CANmessage (data frame) to be transmitted to the second network, andselects a port to send out the frame based on the E-message, based onthe results of the distinguishing. That is to say, in a case where anE-message received by the reception unit 110 does not include CANmessage information, the transfer destination selecting unit 120 bselects one of the ports 1 through 3 as the sending destination ofE-messages having the same content as that E-message, based on thedestination MAC address in the header of the E-message. The transferdestination selecting unit 120 b performs selection of the ports 1through 3 by referencing a MAC address table.

In a case where an E-message received by the reception unit 110 includesCAN message information, the transfer destination selecting unit 120 bselects one of ports 4 and 5 as the destination to send the CAN messagebased on that CAN message information, in accordance with an addresseetable. In a case where a CAN message has been received by the receptionunit 110, the transfer destination selecting unit 120 b selects one ofports 4 and 5 as the transfer destination of that CAN message, inaccordance with the addressee table. FIG. 19 illustrates an example ofan addressee table that the hub 100 b uses. In the example in FIG. 18,the addressee table is a table where transmission sources of receivedframes, CAN-IDs in a case where the frame is a CAN message, and theaddressee of the frame are correlated. In a case where a received frameis an E-message, the transmission source of the received frame indicatesthe transmission source MAC address, and in a case where the frame is aCAN message, indicates the CAN port where that frame was received (CANport 1 or CAN port 2). In the example in FIG. 19, the transferdestination selecting unit 120 b selects the CAN port 2 in a case ofhaving received an E-message containing CAN message information withCAN-ID “0x123” from an E-ECU having MAC address 1, as the sendingdestination of the CAN message based on that CAN message information. Ina case of having received an E-message containing CAN messageinformation from an E-ECU having MAC address 2, the transfer destinationselecting unit 120 b selects both CAN port 1 and CAN port 2 as thesending destination of the CAN message based on that CAN messageinformation. In a case of having received a CAN message with CAN-ID“0X345” or CAN-ID “0x456” from the CAN port 1, the transfer destinationselecting unit 120 b selects the CAN port 2 as the transfer destinationof that CAN message.

The transmission unit 130 includes the E-transmission unit 131,C-transmission unit 132, linking unit 133, and splitting unit 134. In acase where one or both of the port 4 (CAN port 1) and port 5 (CAN port2) has been selected by the transfer destination selecting unit 120 b,the C-transmission unit 132 transmits a CAN message based on CAN messageinformation in a received E-message, or a received CAN message, to theselected port.

Note that the hub 100 b may have a function of generating E-messagesbased on CAN messages received by the C-reception unit 112, andtransmitting from one of the ports 1 through 3.

3.3 Advantages of Third Embodiment

In the onboard network system 10 according to the third embodiment, theE-ECU 200 a transmits an E-message including CAN message information, aCAN flag, and so forth, when transmitting information to a C-ECU. Thisenables the hub 100 b to appropriately select the transmissiondestination of the CAN message indicated in the E-message.

The hub 100 b according to the third embodiment also has a function oftransferring CAN messages among CAN busses, so the number of devicesconfiguring the onboard network can be reduced. Reduction of the numberof devices installed in the vehicle yields advances such as reduction incosts, suppressed malfunction rates, and so forth. The hub 100 b alsoselects a CAN bus from which a CAN message should be sent, from a CAN-IDincluded in the CAN message information or the like. Accordingly,transmission of information is realized by the E-ECU 200 a including aCAN-ID corresponding to the C-ECU to which the information is to betransmitted, in an E-message.

Fourth Embodiment

An example where the ECUs (E-ECU 200 a, etc.) and hub 100 in the onboardnetwork system 10 illustrated in the first embodiment have beenpartially modified will be described below. An example has beenillustrated in the first embodiment where, in a case of the E-ECU 200 atransmitting an E-message containing CAN message information, multipleCAN message information can be included in the E-message, as in FIG. 5for example. Conversely, in the present embodiment, in a case of theE-ECU 200 a including CAN message information in an E-message, only oneCAN message information can be included in the E-message, as in FIG. 4.Note that the E-ECU 200 b and E-ECU 200 c are the same as the E-ECU 200a.

The onboard network system according to a third embodiment is anarrangement where the hub 100 in the onboard network system 10illustrated in the first embodiment (see FIG. 1) has been replaced by ahub 100 c (described later) where the hub 100 has been partiallymodified. Note that components in the onboard network system accordingto the present embodiment that are the same as those in the firstembodiment are denoted by the same reference numerals as in the firstembodiment, and description will be omitted, Points regarding theonboard network system according to the present embodiment that are notdescribed in particular as the same as in the onboard network system 10illustrated in the first embodiment.

4.1 Configuration of Hub 100 c

FIG. 20 is a configuration diagram of the hub 100 c. The hub 100 c has aconfiguration where the transmission unit 130 of the hub 100 illustratedin the first embodiment has been replaced by a transmission unit 130 b.The hub 100 c is configured including the reception unit 110, transferdestination selecting unit 120, and transmission unit 130 b, asillustrated in FIG. 20. These components are realized by communicationcircuits in the hub 100 c, memory, digital circuits (or a processorexecuting programs stored in the memory), and so forth.

The transmission unit 130 b includes the E-transmission unit 131 andC-transmission unit 132. The E-transmission unit 131 has a function oftransmitting E-messages from ports 1 through 3, and the C-transmissionunit 132 has a function of transmitting CAN messages from the port 4 inaccordance with the CAN protocol. Specifically, in a case where the portselected by the transfer destination selecting unit 120 regarding anE-message received by the reception unit 110 is port 4 (CAN port) forexample, the C-transmission unit 132 generates a CAN message based onthe CAN message information included in the received E-message, andsends this CAN message out from the port 4 to the bus 30 c. Note thatthe hub 100 c may also have a function of generating an E-message basedon a CAN message received at the C-reception unit 112 and transmittingfrom one of the ports 1 through 3.

4.2 Operations of E-ECU

FIG. 21 is a flowchart illustrating E-ECU processing, as an example ofoperations of an E-ECU according to the present embodiment. E-ECUprocessing executed by the E-ECU 200 a will be described below by way ofFIG. 21. Note that processing steps in the E-ECU processing according tothe present embodiment that are the same as those illustrated in thefirst embodiment (see FIG. 11) are denoted in FIG. 21 with the samesymbols as in FIG. 11, and description will be omitted here asappropriate.

The E-ECU 200 a receives external information from the reception unit210 (step S1), and performs generating of various types of informationto be transmitted to another ECU at the data processing unit 221 (stepS2), The E-ECU 200 a determines, regarding each information generated bythe data processing unit 221 whether the transmission destination of theinformation is a C-ECU or not in accordance with the data type of theinformation, using an addressee table (step S3). In a case where thetransmission destination of the information is a C-ECU, the E-ECU 200 asets a CAN-ID in accordance with the data type of the information, andgenerates CAN message information indicating the CAN-ID, the dataindicating the information generated by the data processing unit 221,and the size of the data, using the CAN message constructing 224 (stepS4).

In a case of having determined in step S3 that the transmissiondestination is a C-ECU, the E-ECU 200 a constructs an E-messageincluding one CAN message information generated in step S4 in thepayload, using the message constructing unit 223 (step S7). In a casewhere the E-ECU 200 a has determined in step S3 that the transmissiondestination is not a C-ECU, in step S7 an E-message including the dataindicating the information generated by the data processing unit 221 inthe payload is constructed by the message constructing unit 223.

The E-ECU 200 a transmits the E-message generated in step S7 to thecable 20 a by the transmitting unit 230 (step S8). The E-messagetransmitted by the E-ECU 200 a will be received by the hub 100 c. Notethat the E-ECU 200 b and E-ECU 200 c can also operate in the same way asthe E-ECU 200 a.

4.3 Operations of Hub 100 c

FIG. 22 is a flowchart illustrating hub processing, as an example ofoperations of the hub 100 c. hub processing executed by the hub 100 cwill be described below by way of FIG. 22. Note that processing steps inthe hub processing according to the present embodiment that are the sameas those illustrated in the first embodiment (see FIG. 12) are denotedin FIG. 22 with the same symbols as in FIG. 12, and description will beomitted here as appropriate.

The hub 100 c receives an E-message from one of ports 1 through 3 (stepS11), and determines whether or not CAN message information is includedin this E-message (step S12 a). This determination may be performedbased on whether or not the CAN flag is ON, for example, or whether ornot the destination MAC address of the header of the E-message is theparticular address illustrated in the first embodiment or the like, forexample.

In a case where determination is made in step S12 a that CAN messageinformation is not included in the received E-message, the hub 100 cuses the MAC address table to select a port corresponding to thedestination E-ECU, using the transfer destination selecting unit 120(step S13), sends out the same E-message as the received E-message fromthe selected port (step S14), and ends processing of handling thereceived E-message.

In a case of having determined in step 312 a that CAN messageinformation is included in the received E-message, the hub 100 cgenerates a CAN message based on the CAN message information included inthe received E-message (step S17). In a case where the CAN messageinformation is configured of CAN-ID, size, and data (see FIG. 4), forexample, the hub 100 c generates a CAN message including the CAN-ID,size, and data (See FIG. 6). The hub 100 c then sends out the generatedCAN message to the bus 30 c from the port 4 (CAN port) so as to betransmitted to the CAN gateway 400 (step S18), and ends processing ofhandling the received E-message. Upon a CAN message having been sentfrom the hub 100 c to the bus 30 c, the CAN gateway 400 transfers thatCAN message to both or one of the bus 30 a and bus 30 b, for example,based on transfer rules decided beforehand.

4.4 Advantages of Fourth Embodiment

In a case where the E-ECU 200 a is to transmit information to a C-ECU inthe onboard network system 10 according to the fourth embodiment, anE-message is transmitted that incudes CAN message information, a CANflag, and so forth. Accordingly, the hub 100 c will be able toappropriately select the destination of the CAN message indicated by theE-message. By the E-ECU 200 a including CAN message information for oneCAN message in the E-message, the hub 100 c does not have to bear theload of processing such as splitting the contents of the payload of theE-message that has been received.

Fifth Embodiment

A modification of the E-ECU 200 a and hub 100 illustrated in the firstembodiment will be described. An arrangement has been made in the firstembodiment where, in a case of the transmission destination determiningunit 222 in the generating unit 220 of the E-ECU 200 a having determinedthat the ECU to be the destination of information in the addressee tablein FIG. 8 is a C-ECU, a particular address that has been decidedbeforehand is notified to the message constructing unit 223 as thedestination MAC address. Although a broadcast address, multicastaddress, and so forth, have been exemplified as the particular addressin the first embodiment, an example of using a local MAC address as theparticular address will be described in a fifth embodiment. A local MACaddress is where the value of a bit in a MAC address for identifyingwhether or not a global MAC address has been set to a value that is nota global MAC address.

For example, the E-ECU 200 a may use an addressee table such asillustrated in FIG. 23. The addressee table in FIG. 23 has a destinationMAC address correlated with each data type, and a local MAC address suchas “02:aa:bb:cc:01:23”, “02:aatb:cc:02:34”, or the like is included asthe destination MAC address. In this example, the data type to which thelocal MAC address has been correlated is information to be transmittedto the C-ECU.

In a case of generating an E-message with the first information (CANmessage information) included, the generating unit 220 of the E-ECU 200a includes, as the destination MAC address in the header of theE-message, a particular value (particular address or the like) set toindicate second information that represents that the E-message includesfirst information to be transmitted to the second network. Thisparticular value may be the particular address illustrated in the firstembodiment, or may be a data value where the value of a bit in a MACaddress for identifying whether or not a global MAC address has been setto a value that is not a global MAC address (local MAC address). Thirdinformation representing part of a CAN message, such as CAN-ID or thelike, may be included using this data value (local MAC address) forexample, thereby reducing the content of the CAN message informationincluded in the payload of the E-message. For example, the generatingunit 220 may set a data value representing a CAN-ID as the destinationMAC address of the E-message, and set CAN message information thatincludes size and data but does not include the CAN-ID in the payload.

An arrangement may also be made where the hub 100 judges whether or notCAN message information is included in a received E-message not bywhether or not the CAN flag is set to ON, but by whether or not aparticular value such as described above (e.g., a local MAC address orthe like) is set in the destination MAC address in the header of theE-message. Accordingly, whether or not information to be transmitted tothe second network is included in the payload can be distinguishedsimply by referencing the header of the E-message, and in a case wherethe payload of the E-message is encrypted for example, processing can besimplified (decryption can be omitted, etc.). The hub 100 may alsoidentify the CAN-ID using the correlation table illustrated in FIG. 24,based on the particular value set in the destination MAC address in theheader of the E-message (e.g., a local MAC address or the like). FIG. 24illustrates a correlation table where MAC addresses and CAN-IDs havebeen correlated.

FIG. 25 is a flowchart illustrating hub processing, as an example ofoperations of a modified hub 100 according to the present embodiment.hub processing by a modified hub 100 will be described below withreference to FIG. 15. Note that in the hub processing according to thepresent embodiment, processing steps the same as those illustrated inthe first embodiment (see FIG. 12) are denoted in FIG. 25 with the samesymbols as in FIG. 12, and description will be omitted here asappropriate. Also, description will be made under the assumption thatthe generating unit 220 of the E-ECU 200 a sets a data valuecorresponding to the CAN-ID as the destination MAC address in theE-message (local MAC address), and one CAN message information is set inthe payload including size and data but not including the CAN-ID.

The modified hub 100 receives an E-message from one of the ports 1through 3 (Step S11), and determines whether or not CAN messageinformation is included in that E-message by whether the destination MACaddress of the header is the particular value (step S12 b). Thisdetermination may be made by determination based on whether or not thedestination MAC address is the above-described particular address, forexample, or may be determined based on just the value of a bit foridentifying whether or not the destination MAC address is a global MACaddress or not.

In a case where the modified hub 100 has determined in step S12 b thatCAN message information is not included in the received E-message (in acase of having determined that the destination MAC address of the headeris not the particular value), the transfer destination selecting unit120 uses the MAC address table to select a port corresponding to thedestination E-ECU (step S13), sends out the same E-message as thereceived E-message from the selected port (step S14), and endsprocessing regarding the received E-message.

In a case where the modified hub 100 has determined in step S12 b thatCAN message information is included in the received E-message (in a caseof having determined that the destination MAC address of the header isthe particular value), a CAN-ID is obtained from that destination MACaddress based on the correlation table (see FIG. 24) (step S21). Notethat any method may be used as a method to obtain a CAN-ID from thedestination MAC address that is the particular value, Besides the methodof using the correlation table, the method for obtaining this CAN-ID maybe a method where the E-ECU 200 a that is the transmission source of theE-message sets the particular value such that the CAN-ID is included inpart of the destination MAC address, and the modified hub 100 extractsthe CAN-ID from this destination MAC address, for example.Alternatively, a method may be used where the E-ECU 200 a transmits anE-message where a particular value that is the result of a predeterminedcomputation with regard to the CAN-ID is set as the destination MACaddress, and the modified hub 100 calculates the CAN-ID from thedestination MAC address by computation corresponding to thepredetermined computation.

Next, the modified hub 100 generates a CAN message based on the CAN-IDobtained in step 321, and the size and data that is the CAN messageinformation in the payload of the E-message that has been received (stepS17 a). The modified hub 100 then sends the generated CAN message to thebus 30 c from the port 4 (CAN port), thereby transmitting the CANmessage to the CAN gateway 400 (step S18), and the processing ofhandling the received E-message ends.

Thus, the transmission unit 130 of the modified hub 100 performs sendingof a CAN message, which includes first information (CAN messageinformation) in an E-message received at the reception unit 110 to thebus 30 c, by placing a CAN-1D identified based on the value of thedestination MAC address in the header of the E-message in the ID filedof the CAN message, placing data (data field value) that the CAN messageinformation indicates in the data field of the CAN message, and sendingthe generated CAN message out to the bus 30 c.

Other Embodiments

The first through fifth embodiments have been described above asexamples of technology relating to the present disclosure. However, thetechnology relating to the present disclosure is not restricted tothese, and embodiments where modification, substitution, addition,omission, and so forth have been made as appropriate are alsoapplicable. For example, the following modifications are also includedin an embodiment of the present disclosure.

(1) Although description has been made in the above embodiments wherethe E-ECU 200 a places first information (CAN message information) madeup of a CAN flag, CAN-ID, size, and data, in the payload of an E-message(see FIGS. 4 and 5), an arrangement may be made where a CAN flag, andfirst information (CAN message information) serving as a set of datathat is the content of the data field in a CAN message (also referred toas individual data here) are placed in the payload, as illustrated inFIG. 26. In a case where first information is included in the payload,the CAN flag is set to ON for example, and used as second informationindicating that first information is included. In this case, the hub 100can identify the contents of individual CAN messages out of the set ofthe individual data in the payload of the received E-message: using thecorrelation table exemplarily illustrated in FIG. 27, and transmit CANmessages. The example in FIG. 27 indicates that individual data, whichis data (contents of the data field) of a CAN message of which theCAN-ID is “0x123”, is disposed from the second byte of the payload ofthe E-message, and has a size of two bytes. This also indicates thatindividual data, which is data (contents of the data field) of a CANmessage of which the CAN-ID is “0x234”, is disposed from the first byteof the payload of the E-message, and has a size of one byte.Specifically, in this case, the transmission unit 130 of the hub 100sends out the CAN message to the bus 30 c by placing, with regard toeach set of individual data included in an E-message that the hub 100has received, a CAN-ID identified based on placement of the individualdata in the payload, in the ID field of the CAN message, placing thevalue of the individual data in the data field of the CAN message, andsending out the CAN message thus generated to the bus 30 c. Accordingly,the E-ECU 200 a can transmit individual data to C-ECUs by placingindividual data in the payload of E-messages and transmitting, inaccordance with a correlation table the same as with the hub 100. Notethat an arrangement may be made regarding the correlation tableexemplarily illustrated in FIG. 27 where a flag is provided indicatingwhether or not each individual data is valid, and the hub 100 onlyextracts valid individual data and transmits. Alternatively, anarrangement may be made where the E-ECU 200 a does not have acorrelation table the same as with the hub 100, and transmits E-messageshaving a payload configured using the same format for cases oftransmitting information to E-ECUs. and transmitting to C-ECUs. In thiscase, an arrangement may be made where the correlation table that thehub 100 uses (see FIG. 27) may be appropriately set beforehand inaccordance with the data configuration of E-messages that the E-ECU 200a transmits to C-ECUs.

(2) The onboard network system 10 illustrated in the above-describedfirst embodiment may include one or multiple of the hub 100 aillustrated in the above-described second embodiment, besides the hub100. FIG. 28 illustrates an example where a hub 100 a is disposedbetween the E-ECU 200 a and hub 100. In this onboard network, E-messagesincluding CAN message information transmitted by the E-ECU 200 a passthrough the hub 100 a in the first network and reach the hub 100. Inthis case, the hub 100 a handles the hub 100 in the same way as theconversion device 700 in the second embodiment. The hub 100 generatesCAN messages based on CAN message information in received E-messages,and transmits to the CAN bus 30 c making up the second network. Thus,CAN messages reach C-ECUs via the CAN gateway 400, for example.

(3) Although an onboard network system has been illustrated in theabove-described embodiments, the above-described devices such as theECUs (E-ECUs and C-ECUs), hub, conversion device, and so forth, may beused in various types of network communication systems such as inrobots, industrial devices, and so forth.

(4) Description has been made in the above embodiments regarding anarrangement where an onboard network includes a first network and asecond network, the first network transmitting E-messages (Ethernet(registered trademark) frames) following the Ethernet (registeredtrademark) protocol and the second network transmitting CAN messages(data frames) over a CAN bus following the CAN protocol. This CANprotocol is to be understood to have a broad meaning, encompassingderivative protocols such as CANOpen used in embedded systems withinautomation systems and so forth, TTCAN (Time-Triggered CAN), CANFD (CANwith Flexible Data Rate) and so forth. Data frames in the CAN protocolmay be in an extended ID format, besides in the standard ID format. Inthe case of an extended ID format, the 29 bits of the base ID in the IDfield in the standard ID format, and the extended ID, having beencombined, can be used as the CAN-ID in the above-described embodiments.Ethernet (registered trademark) frames may be Ethernet (registeredtrademark) Version 2 frames, or may be frames stipulated by IEEE 802.3,for example. The Ethernet (registered trademark) protocol may beunderstood to have a broad meaning, encompassing derivative protocolssuch as Ethernet (registered trademark) Audio Video Bridging (AVB)relating to IEEE 802.1, Ethernet (registered trademark) Time SensitiveNetworking (TSN) relating to IEEE 802.1, Ethernet (registeredtrademark)/Industrial Protocol (IP), Ethernet (registered trademark) forControl Automation Technology (EtherCAT (registered trademark)), and soforth. An arrangement may be made where the first network transmitsfirst-type frames (e.g., E-messages or the like) following a firstcommunication protocol, and the second network transmits second-typeframes (e.g., CAN messages or the like) over a bus following a secondcommunication protocol that differs from the first communicationprotocol. In this case, the first communication protocol is the Ethernet(registered trademark) protocol for example, but is not restricted tothe Ethernet (registered trademark) protocol, and may be a BroadR-Reachprotocol, for example. Also, the second communication protocol is theCAN protocol for example, but is not restricted to the CAN protocol, andmay be Local interconnect Network (LIN), Media Oriented SystemsTransport (MOST (registered trademark)), FlexRay (registered trademark),and so forth, for example. Note that the Ethernet (registered trademark)illustrated in the above embodiments has a faster communication speedthan CAN. With respect to this point, the first communication protocolmay be various types of protocols that have faster communication speedsthan the second communication protocol. Although an arrangement has beendescribed in the above embodiments where a first-type frame (e.g.,E-message) has an identification flag (e.g., an CAN flag) fordistinguishing whether or not the payload of that first-type frameincludes first information (e.g., CAN message information) serving as abase for a second-type frame (e.g., CAN message) to be transmitted tothe second network, the identification flag may be included in theheader of the first-type frame. For example, the E-ECU 200 a may includethe CAN flag in the header of an E-message. Accordingly, whether or notinformation to be transmitted to the second network is included in thepayload can be distinguished simply by referencing the header of theE-message, and in a case where the payload of the E-message is encryptedfor example, processing can be simplified (decryption can be omitted,etc.). For example, the bit for distinguishing whether or not a globalMAC address in the destination MAC address within the header of theE-message may be used as a CAN flag. Also, for example, a CAN flag maybe set in the type field within the header of the E-message. Also, forexample, the E-ECU 200 a may include a CAN flag both within the headerand within the payload of the E-message.

(5) In above-described the third embodiment, an example has beenillustrated where, in a case of a received E-message containing CANmessage information, the hub 100 b selects the CAN port for transmittinga CAN message, in accordance with the transmission source MAC addresscontained in the E-message and the CAN-ID included in the CAN messageinformation of the E-message, according to an addressee table (see FIG.19). Other than this example, the CAN port for transmitting the CANmessage may be selected from the transmission source MAC addresscontained in the E-message and the destination MAC address, or the CANport for transmitting the CAN message may be selected from thedestination MAC address and CAN-ID. In a case of having received a CANmessage from a CAN port, the hub 100 b may select one of ports 1 through5 as the transfer destination of that CAN message, in accordance withthe CAN port and the CAN-ID included in the CAN message. In this case,if the hub 100 b selects ports 1 through 3, the contents of the CANmessage are included in an E-message and transmitted.

(6) Although an example has been illustrated in the above-describedembodiments where the E-ECU 200 a has a function of transmittingE-messages that include CAN message information and a function oftransmitting E-messages that do not include CAN message information, anarrangement may be made where the E-ECU 200 a does not have the functionof transmitting E-messages that do not include CAN message information.

(7) Although the hubs (hub 100, etc.) illustrated in the above-describedembodiments are switches (switching hubs), the function of switchingdoes not need to be had. That is to say, an arrangement may be madewhere a hub does not distinguish destination MAC addresses ofE-messages, and in a case of having received from one port an E-messagein which the CAN flag is not ON for example, that E-message istransferred to all ports to which Ethernet (registered trademark) cablesare connected other than that port. This does away with the need for thehub to store a MAC address table for example, enabling reduction inmemory.

(8) Although an example has been illustrated in the above-describedembodiments where the CAN message information included in E-messagestransmitted by E-ECUs is made up of CAN-ID, size, and data, the CANmessage information may be made up of any elements as long asinformation serving as the base for generating a CAN message isincluded. For example, the CAN message information may be made up of theelement group following the CAN message format stipulated in ISO11898-1(The SOF, CAN-ID, RTR, IDE, r, size, data, and so on through EOFillustrated in FIG. 6). The processing load at the hub or conversiondevice at the time of transmitting CAN messages to the CAN bus based onE-messages can be reduced by the E-ECUs including CAN messageinformation configured following the CAN message format in E-messagesand transmitting. The CAN message information may be made up ofinformation indicating the data (the contents of the data field) of aCAN message, for example.

(9) Although an example has been illustrated in the above-describedembodiments where the hub 100 and so forth transmit CAN messages inaccordance with multiple CAN message information contained in thepayload of a received E-message, in the order of array of the CANmessage information, the order of transmission of CAN messages is notrestricted to this. For example, at the time of having received anE-message containing multiple CAN message information, the hub 100 orthe like may transmit CAN messages in the order of smallest CAN-IDsbased on the CAN message information or may transmit CAN message at atransmission order based on an order of priority decided beforehand foreach CAN-1D. For CAN messages that need to be periodically transmitted,the hub 100 or the like may wait till the next periodic transmissionperiod to transmit. In a case where the hub 100 or the like decides thetransmission order of CAN messages, the E-ECU 200 a or the like does notneed to perform processing taking the transmission order of CAN messagesin to consideration when transmitting E-messages containing multiple CANmessage information.

(10) The order of executing the procedures for various types ofprocessing illustrated in the above-described embodiments (e.g., thepredetermined procedures and the like illustrated in FIGS. 11, 12, 21,22, and 25) is not necessarily restricted to the above-described order,and the order of execution may be switched around, multiple proceduresmay be executed in parallel, part of the procedures may be omitted, andso forth, without departing from the essence of the disclosure.

(11) Devices in the above-described embodiments, such as ECUs, hubs,conversion devices, and so forth, may include other hardware componentssuch as a hard disk device, display, keyboard, mouse, and so forth. Thefunctions of the device may be realized through software by programsstored in memory being executed by a processor, or the functions may berealized by dedicated hardware (digital circuits or the like).Assignation of functions among the components within the device ischangeable.

(12) Part or all of the components configuring the devices in theabove-described embodiments may be configured as a single system largescale integration (LSI). A system LSI is a super-multi-functional LSImanufactured integrating multiple components on a single chip, andspecifically is a computer system configured including a microprocessor,ROM, RAM, and so forth. A computer program is recorded in the RAM. Thesystem LSI realizes its functions by the microprocessor operatingaccording to the computer program. The parts of the components making upthe above devices may be individually formed into one chip, or part orall may be included in one chip. While description has been maderegarding a system LSI, there are different names such as IC, LSI, superLSI, and ultra LSI, depending on the degree of integration. The circuitintegration technique is not restricted to LSIs, and dedicated circuitsor general-purpose processors may be used to realize the same. A fieldprogrammable gate array (FPGA) which can be programmed aftermanufacturing the LSI, or a reconfigurable processor where circuit cellconnections and settings within the LSI can be reconfigured, may beused. Further, in the event of the advent of an integrated circuittechnology which would replace LSIs by advance of semiconductortechnology or a separate technology derived therefrom, such a technologymay be used for integration of the functional blocks, as a matter ofcourse. Application of biotechnology is a possibility.

(13) Part or all of the components of which the above-described devicesare configured may be configured as an IC card detachably mountable toeach device or a standalone module. The IC card or module is a computersystem configured including a microprocessor, ROM, RAM, and so forth.The IC card or module may include the above-describedsuper-multifunctional LSI. The IC card or module achieves its functionsby the microprocessor operating according to the computer program. TheIC card or module may be tamper-resistant.

(14) One aspect of the present disclosure may be, for example, a framegenerating method including all or part of the processing proceduresillustrated in FIGS. 11, 21, and so forth, or may be a transfer methodincluding all or part of the processing procedures illustrated in FIGS.12, 22, 25, and so forth. For example, the frame generating method maybe, for example, a frame generating method where an ECU connected to afirst network generates frames that are transmitted, in a network systemincluding the first network where transmission of first-type frames isperformed following a first communication protocol (e.g., the Ethernet(registered trademark) protocol) and a second network where transmissionof second-type frames is performed over the bus following a secondcommunication protocol (e.g., the CAN protocol) that is different fromthe first communication protocol, the first-type frames being generatedfollowing the first communication protocol such that first informationserving as the base of the second-type frames to be transmitted to thesecond network, and second information indicating that the first-typeframes include information to be transmitted to the second network, areincluded in the first-type frames. Also, for example, the transfermethod is a transfer method used at a network hub in a network systemincluding a first network where transmission of first-type frames isperformed following a first communication protocol and a second networkwhere transmission of second-type frames is performed over the busfollowing a second communication protocol that is different from thefirst communication protocol, the transfer method including a receptionstep of receiving a first-type frame, a transfer destination selectingstep of distinguishing whether or not the first-type frame received inthe reception step includes first information serving as a base for asecond-type frame that is to be transmitted to the second network, andselecting a port for sending out a frame based on this first-type frameaccording to the results of the determining, and a transmission step oftransmitting a frame based on this first-type frame to a wired transferpath connected to the port selected in the transfer destinationselecting step, with regard to the first-type frame received in thereception step. The method may be a program (computer program) whichrealizes this method by a computer, or may be digital signals made up ofthe computer program. For example, the transfer method may be a programthat includes a generating step according to the frame generating method(a step of generating the first-type frame following the firstcommunication protocol) and a transmitting step (a step of transmittingthe first-type frame generated in the generating step to the firstnetwork), wherein the generating step, predetermined informationprocessing to generate the first-type frame is executed such that thefirst-type frame includes first information serving as a base for thesecond-type frame to be transmitted to the second network, and secondinformation indicating that the first-type frame includes information tobe transmitted to the second network. An aspect of the presentdisclosure may be the computer program or the digital signals recordedin a computer-readable recording medium, such as for example, a flexibledisk, a hard disk, a CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, BD (Blu-ray(registered trademark) Disc), semiconductor memory, or the like. Thepresent disclosure may also be the digital signals recorded in theserecording mediums. An aspect of the present disclosure may be anarrangement where the computer program or the digital signals aretransmitted over an electric communication line, wireless or cablecommunication line, a network of which the Internet is representative,data broadcasting, or the like. Also, an aspect of the presentdisclosure may be a computer system having a microprocessor and memory,where the memory records the computer program, and the microprocessoroperates according to the computer program. The program or the digitalsignals may be recorded in the recording medium and transported, or theprogram or the digital signals may be transported over the network orthe like, and thereby be executed by another computer system that isindependent.

(15) Forms realized by optionally combining the components and functionsdescribed in the above embodiments and the above modifications are alsoincluded in the scope of the present disclosure.

The present disclosure is applicable to an ECU transmitting informationto other ECUs connected to a bus in a second network such as a CAN orthe like, via a first network such as Ethernet (registered trademark) orthe like.

What is claimed is:
 1. An electronic control unit (ECU) connected to afirst network in an onboard network system, the onboard network systemincluding the first network for transmission of a first-type framefollowing a first communication protocol, and including a second networkfor transmission of a second-type frame following a second communicationprotocol that is different from the first communication protocol, theelectronic control unit comprising: a generator that generates thefirst-type frame following the first communication protocol; and atransmitter that transmits, to the first network, the first-type framegenerated by the generator, wherein the first-type frame includes firstinformation serving as a base for the second-type frame to betransmitted to the second network, and second information indicatingthat the first-type frame includes information that is to be transmittedto the second network, wherein the first communication protocol is anEthernet protocol, wherein the second communication protocol is aController Area Network (CAN) protocol, wherein the first-type frame isan Ethernet frame including an Ethernet header and data that is apayload, wherein the second-type frame is a data frame including a datafield, wherein the first information indicates content of the datafield, wherein the generator includes the first information in thepayload of the first-type frame, and wherein, when generating thefirst-type frame including the first information, the generatorindicates the second information by setting a value of a bit in adestination MAC address in the Ethernet header in the first-type frame,to a value indicating a non-global MAC address, and the first-type frameincludes third information indicating a part of content of thesecond-type frame in the destination MAC address.
 2. The electroniccontrol unit according to claim 1, wherein the generator, in thegenerating of the first-type frame, places an identification flag in thefirst-type frame for identifying whether or not the first-type frameincludes information that is to be transmitted to the second network,and when generating the first-type frame including the firstinformation, sets the identification flag in the first-type frame to avalue indicating the second information.
 3. The electronic control unitaccording to claim 2, wherein the generator places the identificationflag in the payload in the generating of the first-type frame.
 4. Theelectronic control unit according to claim 1, wherein, when generatingthe first-type frame including the first information, the generatorincludes a particular value set to indicate the second information asthe destination MAC address in the Ethernet header in the first-typeframe.
 5. The electronic control unit according to claim 1, wherein thesecond-type frame includes an ID field, a data length code (DLC), andthe data field, and wherein the first information indicates the H)field, the DLC, and a value of the data field.
 6. The electronic controlunit according to claim 5, wherein the first information indicates, foreach of a plurality of second-type frames to be transmitted to thesecond network, the ID field, the DLC, and the value of the data field,and a quantity of the plurality of second-type frames.
 7. A framegenerating method of generating a frame to be transmitted, by anelectronic control unit connected to a first network in an onboardnetwork system, the onboard network system including the first networkfor transmission of a first-type frame following a first communicationprotocol, and including a second network for transmission of asecond-type frame following a second communication protocol that isdifferent from the first communication protocol, the method comprising:generating, by the electronic control unit, the first-type framefollowing the first communication protocol; and transmitting, by theelectronic control unit, the first-type frame to the first network,wherein the first-type frame includes first information serving as abase for the second-type frame to be transmitted to the second network,and second information indicating that the first-type frame includesinformation that is to be transmitted to the second network, wherein thefirst communication protocol is an Ethernet protocol, wherein the secondcommunication protocol is a Controller Area Network (CAN) protocol,wherein the first-type frame is an Ethernet frame including an Ethernetheader and data that is a payload, wherein the second-type frame is adata frame including a data field, wherein the first informationindicates content of the data field, wherein, in the generating,including the first information in the payload of the first-type frame,and wherein, when generating the first-type frame including the firstinformation, indicating the second information by setting a value of abit in a destination MAC address in the Ethernet header in thefirst-type frame, to a value indicating a non-global MAC address, andthe first-type frame includes third information indicating a part ofcontent of the second-type frame in the destination MAC address.
 8. Anon-transitory computer-readable recording medium storing a program forcausing an electronic control unit (ECU) that includes a microprocessorand that is connected to a first network in an onboard network system,the onboard network system including the first network for transmissionof a first type frame following a first communication protocol, andincluding a second network for transmission of a second-type framefollowing a second communication protocol that is different from thefirst communication protocol, to perform predetermined processingcomprising: generating the first-type frame following the firstcommunication protocol; and transmitting, to the first network thefirst-type frame generated in the generating, wherein the first-typeframe includes first information serving as a base for the second-typeframe to be transmitted to the second network, and second informationindicating that the first-type frame includes information that is to betransmitted to the second network, wherein the first communicationprotocol is an Ethernet protocol, wherein the second communicationprotocol is a Controller Area Network (CAN) protocol, wherein thefirst-type frame is an Ethernet frame including an Ethernet header anddata that is a payload, wherein the second-type frame is a data frameincluding a data field, wherein the first information indicates contentof the data field, wherein, in the generating, including the firstinformation in the payload of the first-type frame, and wherein, whengenerating the first-type frame including the first information,indicating the second information by setting a value of a bit in adestination MAC address in the Ethernet header in the first-type frame,to a value indicating a non-global MAC address, and the first-type frameincludes third information indicating a part of content of thesecond-type frame in the destination MAC address.